A lack of good grounding is undesirable and increases the risk of equipment failure. The absence of an effective grounding system can lead to various problems, such as instrumentation errors, harmonic distortion issues, power factor problems and a host of possible intermittent dilemmas. If fault currents have no path to the ground through a properly designed and maintained grounding system, they will find unintended paths. Furthermore, a good grounding system is also used to prevent damage to industrial plants and equipment and is therefore necessary in order to improve the reliability of equipment and reduce the likelihood of damage due to lightning or fault currents.
Over time, corrosive soils with high moisture content, high salt content, and high temperatures can degrade ground rods and their connections. So although the ground system may have had low ground resistance values when initially installed, the resistance of the grounding system can increase if the ground rods, or other elements of the grounding system, corrode over time. Grounding testers are useful troubleshooting tools in dealing with such issues as intermittent electrical problems, which could be related to poor grounding or poor power quality. It is therefore desirable that all grounds and ground connections are checked on a regular basis.
During these periodic checks, if an increase in resistance of more than 20% is measured (e.g., one foot of a pylon with four footings has become unintentionally disconnected), investigation of the source of the problem is necessary in order that the respective corrections may be made to lower the resistance (e.g., by replacing or adding ground rods to the ground system). Such periodic checks may involve conducting established techniques such as fall-of-potential tests and selective measurements.
Typical pylons have a plurality of footings (e.g., four), which are used as earth ground rods, and possibly comprise supplementary auxiliary ground rods. The resistance of such earth ground rods must be tested regularly. Often, only the overall earth ground resistance of each pylon, as opposed to each individual footing, is of interest. The earth ground resistance of each individual footing is generally only relevant in the case of substantial variation between respective resistance values measured at different footings of the pylon. Such differences may indicate a failure (i.e., excessive corrosion or damage) of one or more footings. If all footings are connected together by an earth grid, the low loop resistance of all the footings in series with the grid can also be measured with established techniques. This is possible since the assumption can be made that the earth resistance of the correctly connected grid itself is not likely to change dramatically.
Grounding test systems can specifically be implemented for testing the overall resistivity of a plurality of ground rods (i.e., in such applications as the aforementioned footings of high-voltage electricity pylons). The prior art requires an additional adaptor device, which must be connected between the ground rods to be measured and the grounding test device, in order to achieve the aforementioned resistance measurements. Such adaptor units generally require connection to four clamps, each required for attachment to each respective footing of the pylon. An overall resistance of the four footings is then determined. Such adaptors tend to not only be expensive, but also bulky, thus increasing the amount of equipment needed to be transported to a pylon measurement site. Furthermore, such prior art systems are limited to pylons with a maximum of four footings. Since many pylons have additional earth ground rods and footings requiring a minimum of five or more measurements, prior art techniques are unable to provide an effective system for accommodating the measurement of further footings or ground rods. By not taking measurements of the supplemental elements of a pylon grounding system into account, this can lead to inaccurate values for the overall resistance of the pylon. Furthermore, prior art systems also fail to provide a true value for the resistance of the pylon footings.
Also, prior art techniques tend to be extremely time consuming, labor-intensive and costly since it is necessary for current clamps to be connected to each of the plurality of earth ground rods (i.e., footings) to be connected to the testing means, which also need to be connected to an adaptor. Furthermore, in order to increase accuracy, it is also desirable to achieve true values of not only resistances, but also impedances of each individual pylon footing in order to also enable calculation of true resistance and/or impedance values for all footings of a pylon. Therefore, it is an object of the present disclosure to provide a more flexible system which enables the calculation of a value for the true resistance and/or impedance of each footing of multiple footings of a pylon, or pylons, based on the measurements taken.